To build kernel with clang, people typically use make -j60 LLVM=1 LLVM_IAS=1 LLVM_IAS=1 is not required for non-LTO build but is required for LTO build. In my environment, I am always having LLVM_IAS=1 regardless of whether LTO is enabled or not. After kernel is build with clang, the following command can be used to build selftests with clang: make -j60 -C tools/testing/selftests/bpf LLVM=1 LLVM_IAS=1 I am using latest bpf-next kernel code base and latest clang built from source from https://github.com/llvm/llvm-project.git Using earlier version of llvm may have compilation errors, see tools/testing/selftests/bpf due to continuous development in llvm bpf features and selftests to use these features. To run bpf selftest properly, you need have certain necessary kernel configs like at: bpf-next:tools/testing/selftests/bpf/config (not that this is not a complete .config file and some other configs might still be needed.) Currently, using the above command, some compilations still use gcc and there are also compilation errors and warnings. This patch set intends to fix these issues. Patch #1 and #2 fixed the issue so clang/clang++ is used instead of gcc/g++. Patch #3 fixed a compilation failure. Patch #4 and #5 fixed various compiler warnings. Changelog: v2 -> v3: . more test environment description in cover letter. (Sedat) . use a different fix, but similar to other use in selftests/bpf Makefile, to exclude header files from CXX compilation command line. (Andrii) . fix codes instead of adding -Wno-format-security. (Andrii) v1 -> v2: . add -Wno-unused-command-line-argument and -Wno-format-security for clang only as (1). gcc does not exhibit those warnings, and (2). -Wno-unused-command-line-argument is only supported by clang. (Sedat) Yonghong Song (5): selftests: set CC to clang in lib.mk if LLVM is set tools: allow proper CC/CXX/... override with LLVM=1 in Makefile.include selftests/bpf: fix test_cpp compilation failure with clang selftests/bpf: silence clang compilation warnings bpftool: fix a clang compilation warning tools/bpf/bpftool/net.c | 2 +- tools/scripts/Makefile.include | 12 ++++++++++-- tools/testing/selftests/bpf/Makefile | 7 ++++++- tools/testing/selftests/bpf/prog_tests/fexit_sleep.c | 4 ++-- .../selftests/bpf/prog_tests/ns_current_pid_tgid.c | 4 ++-- tools/testing/selftests/lib.mk | 4 ++++ 6 files changed, 25 insertions(+), 8 deletions(-) -- 2.30.2
